1. Field of the Invention
The invention relates to a method and a system for time synchronisation between a control centre and several transmitters, in particular, in a single frequency network.
2. Related Art
Within a single frequency network, as shown FIG. 1 for the operational case of two transmitters 21 and 22, the information to be transmitted is typically bundled by a control centre 1, also referred to as the headend, in an MPEG-2-coded manner in individual data packets of a transport data stream sZen and supplied via a network to the individual, locally distributed transmitters 21, 22, . . . , 2i of the single frequency network. The transmission of the transport data stream sTR1, sTR2, . . . , sTRi by the individual transmitters 21, 22, . . . , 2i of a single frequency network is implemented both in a frequency synchronised manner and also in a time synchronised manner.
The time synchronisation to be considered in the following description considers, in particular, different delay times tTR1, tTR2, . . . , tTRi of the transport data stream sZen between the control centre 1 and the individual transmitters 21, 22, . . . , 2i. In WO 2006/046107 A1, a system and a method are presented for the time synchronisation of a transport data stream within a single frequency network, in which the synchronisation between the individual transmitters is implemented via time information, inserted into the transport data stream by the control centre in constant time intervals, which contain the transmission time of the data packet carrying the time information of the tSende1=tSende2= . . . =tSendei of the data packet carrying the time information of the transport data stream sTR1, sTR2, . . . , sTRi to be transmitted in all transmitters 21, 22, . . . , 2i. On the basis of this time information, the individual transmitter can delay the individual received data packets of the transport data stream sTR1, sTR2, . . . , sTRi continuously in time within the time raster of the transmitted time information by buffering them in a buffer memory 31, 32, . . . , 3i until every individual data packet can be transmitted at its correct transmission time tSendei=tSende2= . . . =tSendei.